How to add reference numbers to exported UV map
The closest I can come up with:
Go to the &quot;UV Editing&quot; work space
Select your object and enter edit mode
Create the UV map.  Here I'll use the default cube and its default unwrapping for simplicity.
Use the UV menu to export the UV Map to a file:

Make sure to check &quot;all UVs&quot; in the file dialog:

Create a new image using the &quot;+ New Button&quot;

Make sure you create a blank image:

Switch to the image editor:

Switch to paint mode:

Use the paint brush to add your annotations:

Save the image to a file:

Now you have two images files, one with the outline of the UV Map, the other with annotations.  Load them into your favorite image editor as layers, with the UV map above the annotations.  Set opacity to taste and you end up with something like this in the image editor:

You can even use this technique to temporarily put the annotations on your model by giving it a material that uses the image you created as an image texture:

Using the shader:

This will even allow you to place the correct orientation for the faces, if they happen to be otherwise indistinguishable.